IDOT changing planting strategy to avoid emerald ash borer

Monday

Sep 29, 2008 at 12:01 AMSep 29, 2008 at 5:10 AM

In an attempt to increase defense against the devastating emerald ash borer, the Illinois Department of Transportation has announced it no longer will plant ash trees as part of its landscape projects.

Erin Wood

In an attempt to increase defense against the devastating emerald ash borer, the Illinois Department of Transportation has announced it no longer will plant ash trees as part of its landscape projects.

An invasive beetle native of Asia, the emerald ash borer is making its way south through the state and already has killed millions of ash trees in northwest Illinois and other states.

"It's spreading at a good speed and will eventually hit the whole state," said IDOT roadside maintenance manager Craig Mitckes. "Rather than be reactive, we want to take a proactive approach. There's no reason to plant trees that may be a future source of infestation for these insects."

Aside from stopping planting of ash trees along highway rights-of-way, Mitckes said crews will remove IDOT-owned infested trees throughout the state. The largest landowner in Illinois, IDOT will provide significant help in battling the overwhelming infestation, said Juliann Heminghous, emerald ash borer outreach coordinator for the Illinois Department of Agriculture.

"They made a decision that we can't invite this problem anymore," she said. "They took a proactive measure to quit planting ash trees, and that shows a lot of responsibility."

Though IDOT may be able to slow the bug's spread, the emerald ash borer promises to continue on its path of destruction, Heminghous said. The metallic green beetle has been confirmed as close as Bloomington, but Peoria's traps haven't yet been taken down or analyzed.

The triangular purple boxes, about the size of microwaves, were placed in ash trees throughout the state beginning in late spring. The process of removing them takes longer, Heminghous said, because the boxes must not touch or they will contaminate other traps' specimens.

About 20 traps fit in a truck bed, and they must all be delivered to DeKalb for inspection. This time-consuming procedure, Heminghous said, could last through October.

But untainted cities still should be preparing for an ash borer invasion, she said. Fall and winter are the seasons when the larvae of the beetle feed on the cambium layer of the trees, depriving it of nutrients and eventually causing its death.

"We want communities to plan for this," she said. "Talk to each other and pool your resources."

Ash trees make up about 10 percent of Peoria's urban tree population, said Roger Troxell, forestry and grounds planner for the city of Peoria. Ash trees haven't been planted in Peoria for about three years because of the ash borer threat, he said, but that doesn't mean his job is finished.

"We're putting a plan together," he said.

Though he declined to discuss specific details about the city's defense strategy, Troxell said preventive measures are not included.

"We're focusing on reforestation and how we're going to go about that," he said. "It's really not cost effective to treat trees annually. We know we'll have to replace them."